Gases such as, for example, bottled industrial gases (nitrogen, argon, oxygen), refrigerants and natural gas, are frequently transported at high pressure, often exceeding 2000 PSIG. For example, bottled industrial gases are frequently at pressures exceeding 2800 PSIG and specialty bottled gases can be over 6000 PSIG. At natural gas fueling installations, natural gas can be supplied to vehicles at pressures exceeding 4000 PSIG. The molecules of natural gas are small, enhancing its ability to permeate through standard rubber or PVC hose constructions used for low pressure fluids, and the permeation of the gas is more rapid as the working pressure increases, which can cause natural gas accumulation with potentially dangerous consequences.
Traditionally, these gases have been transported in lower permeability tubing, such as hard tubing formed of metals or metallic alloys such as, for example, steel, stainless steel, copper and the like or using polymeric tubing such as, for example, nylon tubing. Such tubing must meet certain standards, such as ANSI, ASTM, and/or Underwriter Laboratories (UL®) requirements, to be used for distribution of high pressure gases. For example, hoses used for distribution of natural gas should have a maximum permeability rate of about 20 ml/m/hr.
However, conventional high pressure tubing suffers from drawbacks. For example, metallic tubing can fatigue or corrode over time, which results in catastrophic failure. Polymer hose and tubing such as, for example, Nylon tubing, on the other hand, while typically not subject to catastrophic failure, has the potential for kink formation. Furthermore, polymer hoses can degrade over time, causing an increase in their permeability until the tubing is no longer adequate for use with high pressure gases, i.e. the maximum permeability rate has been exceeded, which can go undetected. In addition, polymeric hoses many not be compatible with high temperatures such as, for example, those found in automotive applications, or low temperature conditions as found in some gas depressurizing applications. As such, it would be advantageous to improve upon existing hose and tubing options for use in transporting high pressure gases.